1 files changed, 43 insertions, 0 deletions

diff --git a/Documentation/watchdog/wdt.txt b/Documentation/watchdog/wdt.txt
new file mode 100644
index 000000000000..03fd756d976d
--- /dev/null
+++ b/Documentation/watchdog/wdt.txt
@@ -0,0 +1,43 @@
+Last Reviewed: 10/05/2007
+
+        WDT Watchdog Timer Interfaces For The Linux Operating System
+                Alan Cox <alan@lxorguk.ukuu.org.uk>
+
+        ICS     WDT501-P
+        ICS     WDT501-P (no fan tachometer)
+        ICS     WDT500-P
+
+All the interfaces provide /dev/watchdog, which when open must be written
+to within a timeout or the machine will reboot. Each write delays the reboot
+time another timeout. In the case of the software watchdog the ability to
+reboot will depend on the state of the machines and interrupts. The hardware
+boards physically pull the machine down off their own onboard timers and
+will reboot from almost anything.
+
+A second temperature monitoring interface is available on the WDT501P cards
+This provides /dev/temperature. This is the machine internal temperature in
+degrees Fahrenheit. Each read returns a single byte giving the temperature.
+
+The third interface logs kernel messages on additional alert events.
+
+The wdt card cannot be safely probed for. Instead you need to pass
+wdt=ioaddr,irq as a boot parameter - eg "wdt=0x240,11".
+
+Features
+--------
+                WDT501P         WDT500P
+Reboot Timer       X               X
+External Reboot    X               X
+I/O Port Monitor   o               o
+Temperature        X               o
+Fan Speed          X               o
+Power Under        X               o
+Power Over         X               o
+Overheat           X               o
+
+The external event interfaces on the WDT boards are not currently supported.
+Minor numbers are however allocated for it.
+
+
+Example Watchdog Driver:  see Documentation/watchdog/src/watchdog-simple.c
+